Mud bath sites of the wild boar (Sus scrofa) were investigated in June-August 2005 on the northern slope of Funiu Mountain.. Fourteen ecological factors (Vegetation type, Elevation, Slope, Location, Aspect, Distance to water source, level of concealment, Distance to human disturbance, Canopy cover, Soil traits, average distance to trees, average distance to shrubs, average distance to tree-falls, average distance to stumps) were recorded in each of 20 m×20 m plots. The data thus collected were analyzed using Cluster Analysis and Principal Component Analysis. The results showed that mud bath sites of the wild boar shared the following characteristics: absence of tree-falls and stumps, high levels of concealment, loess soil, canopy cover > 80%, average distance to trees moderate, average distance to shrubs less than 1 m, slope less than 30, broadleaf forest vegetation, distance to human disturbance greater than 500 m, and altitude greater than 1000 m. There were no obvious preferences concerning location and distance to water source.